Quantifying Soil Re-Deposition, Soil Loss and the Nutrients Associated with Them in Field-Scale Experiments.

Lack of quality soil erosion field data, which is essential for the development, verification and calibration of soil erosion models, is one of the most serious problems and challenges facing soil and water conservation research today. The root of this problem stems from the fact that the current techniques are either obstructing the natural field runoff pattern (e.g. the runoff-plot method) or insensitive to seasonal soil erosion events (e.g., erosion pin and radio-nuclides methods). In order to fill this gap in soil erosion research, we have developed a novel approach based on the principle of a mesh-sheet (MS) method and tested it in a 67 ha. North Florida farm to study soil re-deposition, soil loss and the nutrients associated with them.  The results show that soil re-deposition on the top, mid and bottom slopes were 29%, 62.2% and 7.1%, respectively, of the total soil moved in the June-August of 2010. Soil loss from the 200 m slope was only 1.7% of the total soil moved. Clay and silt content, nitrogen and phosphorous associated with the soil loss, however, were at a much more significant levels of 16.4%, 23% and 19.3%, respectively, of the total amounts moved. Differential losses of fine particles, nitrogen and phosphorus from the slope due to soil erosion, therefore, were very significant and should be included in soil erosion models. The spatial and temporal information of soil re-deposition, soil loss and the nutrients associated with them give us valuable insight into the soil erosion processes in watersheds.